This invention relates generally to industrial fuel blenders and fuel blending methods.
It has long been recognized that certain hydrocarbon additives dramatically improve the heating capacity and flame cutting efficiency of base hydrocarbon fuels such as natural gas and propane. However, in order to enrich base hydrocarbon fuels properly and efficiently the fuel additives must be consistently blended in a proper mix ratio and preferably with minimal waste residual.
Heretofore, as exemplified by co-pending U.S. Pat. Applications Ser. Nos. 679,353 abandoned and 707,519, which are assigned to the assignee of the present application, systems and methods have been developed for pre-blending base hydrocarbon fuels with fuel enriching hydrocarbon additives while both are in their liquid states. A difficulty encountered in doing this properly, however, is attributable to the fact that the additives ordinarily have a higher specific gravity than do the base fuels and thus tend to settle to the bottom of any container in which they are stored in a pre-blended condition.
To avoid the just described problem other blending systems have heretofore been developed as exemplified by that disclosed in U.S. Pat. No. 3,924,648. Here a base fuel is blended in its gaseous state with a fuel enriching additive in its liquid state by percolating the base fuel upwardly through a supply of the liquid additive. Blending efficiency, however, has remained relatively poor with these types of systems due to inconsistent vaporization of the hydrocarbons occasioned by ambient temperature variations. Variations in atmospheric conditions and specific gravity divergencies have also caused post-blending separation and fuel mixture ratio inconsistencies which in turn lead to inconsistencies in operation efficiency and effectiveness as, for example, where the enriched fuel is used for cutting torches. In addition, following apparent exhaustion of fuel additive from their containers, it has heretofore been a very common occurrence to observe, upon container disassembly and inspection, a small supply of residual additive remaining which leads to waste. Furthermore, supply cylinders have also needed frequency maintenance in order to clean a gummy residue left therein resulting from stratification.
Accordingly, it is a general object of the present invention to provide an improved industrial fuel blender and fuel blending method.
More specifically, it is an object of the present invention to provide an improved fuel blender and fuel blending method for blending a base hydrocarbon fuel in its gaseous state with a fuel enriching hydrocarbon additive in its gaseous state.
Another object of the invention is to provide an industrial fuel blender and fuel blending method of the type described with means for inhibiting condensation of gaseous fuel additive during blending operations.
Another object of the invention is to provide a fuel blender and fuel blending method of the type described having simplified means for controlling flow.
Another object of the invention is to provide a fuel blender and fuel blending method of the type described capable of substantially emptying a supply of fuel additive while maintaining the blending ratio of additive to base fuel substantially uniform until additive exhaustion has occurred.
Yet another object of the invention is to provide a fuel blender and fuel blending method of the type described the use of which affects consistent blending under varying ambient temperature and pressure conditions.